This article says there's a biological reason for kissing. Germ transmission!
First, the female becomes the immune to the germs, then the baby. Apparently, even wombats swap saliva.
So, I have a new pickup line. "Hey there, Fresh Lips. Wanna swap some germs?"
Except, with you they're not so much pickup lines as they are call the police lines.
Title-text: Hey, Baby. I've got so many germs, you'll never need to kiss another man again.